MANAUS, Brazil - In the 1980s, scientists sounded the alarm: The Amazon was burning and would be gone by the end of the century.

Two decades later, the dire predictions have not come to pass. Around 80 percent of the world's largest remaining tropical wilderness is still standing - a vast carpet of green crisscrossed by the Amazon river and its 1,100 tributaries.

But scientists warn that the destruction only has slowed, and a Connecticut-sized chunk disappears every year for ranching, farming, and logging.

The reasons for the rain forest's survival have more to do with economics and a political change of fortune than because of the worldwide environmental campaign to save the Amazon.

In the 1980s, Brazil was under a military dictatorship with ambitious plans to develop Brazil's portion of the rain forest - 1.6 million square miles. Had the country not suffered in a massive debt crisis in the late 1980s, "everything would be gone by now," says Philip Fearnside, an US scientist at the Brazilian government's National Institute for Amazon Research.

But that's no reason for complacency, he warns. While the rate of deforestation has dropped dramatically over the past few years, it remains alarmingly high and new threats loom, among them corporate farms armed with the latest agricultural technology to grow soy, raise cattle and plant crops for biofuels.

"Total investment in the region over the last 500 years is equal to what is projected for the next 10," said Joao Meirelles, director of the Peabriu Institute, who estimates private and public sector investments over the next decade will top $50 billion.

The plight of the Amazon, highlighted by celebrities such as pop star Sting, is closely linked to climate change, because every year, burning rain forest releases millions of tons of carbon dioxide, the main greenhouse gas blamed for global warming.

The Amazon is an important absorber of carbon dioxide, and the smaller it gets, the greater the risks to the climate, the World Wide Fund for Nature warned in a report released at the ongoing UN conference on climate change in Bali, Indonesia.

"The importance of the Amazon forest for the globe's climate cannot be underplayed," said Daniel Nepstad, the Amazon-based scientist with the Woods Hole Research Center who wrote the report.

The warnings come as Brazilians are dusting off plans to pave long neglected jungle roads, threatening to open vast swaths of pristine rain forest to development of commodities such as soybeans, sugar cane and iron ore that underpin the Brazilian economy. Scientists say each paved road typically brings with it 30 miles of destruction on each side, and draws influxes of poor settlers in a region where 45 percent of the population lives on $2 a day.